This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We will develop an open, extensible platform for spatial modeling and simulation (VCell Platform). This platform will be constructed based on the plug-in architecture of eclipse (eclipse.org), a powerful and well accepted standards-based component plug-in architecture and comprehensive client application framework. The adoption of this well documented component technology frees us to focus on the careful design of core infrastructure components and a generalized modeling architecture to provide a scaffold for a diverse array of modeling, simulation, and data handling capabilities. Every level (core, abstract services) will define a set of extension points to accommodate future customization by plug-ins. Using this platform, custom problem solving environments can be composed from the same reusable components.